1. Field of the Invention
The present invention relates generally to a device for the control of any electrical machine. More particularly, the present invention relates to regulation control devices or regulation devices. It also relates to machines that are electrically supplied and are, moreover, controlled by a control circuit, with an additional function being added on to this control circuit for these electrical machines.
The invention shall be described with respect to an example where the machine is an electrical radiator. However, it could be any other machine such as a domestic electrical appliance or an industrial machine, having the specific feature of being electrical, supplied by means of an electrical supply (for example the mains) and also possessing a control circuit.
2. Discussion of the Related Art
In the field of the control of electrical machines, especially radiators, there are known ways of carrying out the control functions with electronic circuits, especially electronic circuits including processors or microprocessors associated with program memories and peripheral control circuits. In the field of electrical radiators, there is especially the known circuit called UAA2016 by Motorola that enables the regulation of the thermal power dissipated by a radiator as a function of a measurement of the ambient temperature and an instructed value or set value of temperature indicated by a user through a control button. In practice, the temperature sensor is a CTN type resistor, i.e. with a negative temperature coefficient.
These resistors have the drawback of undergoing variations over time (through the aging of the component). For example, at the end of several years, the signal delivered by the resistor is no longer the same as it was at the outset. Furthermore, a problem of non-linearity arises. To overcome these drawbacks, the above-mentioned circuit includes the possibility of taking account of another resistor of the same type, placed at another position in the vicinity of the radiator (generally at the bottom of the radiator) so as to compensate for the variations or cases of non-linearity. This approach has the drawback wherein the device made is costly because the CTN type resistors are themselves costly in that they have components of the greatest possible linearity. It also has the drawback of requiring lengthy and painstaking research and design work in order to devise the regulation transfer function piloted by this circuit. Indeed, this transfer function depends to a great extent on the geometry of the radiator and especially on the position of the CTN detection resistors at the different places in the radiator. This method also entails one inevitable problem: it does not take account of the size of the room and of the place in the room in which the radiator is located. The circuit concerned, when it fulfills its regulation function, delivers a signal that is transmitted to a circuit for turning on the thermal resistors of the radiator. This circuit for turning on the resistors is ultimately the load circuit of the regulation signal, namely the command signal.
An additional problem arises when, apart from a system of regulation imposed by an operator on a concerned radiator, it is sought to pilot a general heating installation so as to make it work in different modes of operation: for example a comfort mode, during which the temperature, in Celsius, in an entire house should be about 19.degree. or 20.degree., an economical mode during which this temperature should be from 10.degree. to 15.degree. corresponding to periods when the house is inhabited but when there is no one within: for example between 10:00 AM and 4:00 PM for people who have gone to work. It may also be desired to have a so-called minimum "no-freeze" mode corresponding to situations in which there is no one in the house but when, in order to protect the plumbing, it is important not to allow the house to freeze: a minimum temperature of 7.degree. is then set. Finally, there may be an OFF mode in which the installation is permanently stopped and, whatever the commands applied to each of the radiators, they cannot start producing heat.
The circuit referred to here above is not capable of managing this so-called piloting information. Hence, it has become common practice to add an additional microcontroller to this regulation circuit, the signal of which is ultimately a signal to enable or to modify the working of the above-mentioned circuit. This additional microcontroller, by means of a wire known as a pilot wire, receives the information coming from the general control system of the house through which the user lays down a general mode of operation. In practice, the pilot wire may be a wire or a bus, the essential point being that it should convey the information on the mode of operation.
It can then be seen, in this case, that the processing of the information from the pilot wire by the microcontroller takes priority over the regulation carried out by the above-mentioned circuit. The regulation time constant is longer than the duration of the reception of remote control information from the pilot wire which is, firstly, short and, secondly, random. For example, the information from the pilot wire may have a duration of 20 milliseconds. In this case the microcontroller system will be handling an interruption operation. In addition to the obligation of adding the microcontroller, this device remains costly owing to the presence of the two CTN type resistors.
Furthermore, a new standard, in particular the European standard ICE 555-1/2/3, imposes a limit on the value of the reactive impedance generated by the untimely consumption of electrical current from the mains. Indeed, when the voltage is turned on in a machine, it is possible that the phase of the mains will correspond to a voltage or current antinode. Under these conditions, the current drawn is very great and, owing to various types of electrical consumption, gives rise to a distortion of the signal existing in the mains. This distortion leads to the presence of harmonics, notably third harmonics (at 150 Hz) that are detrimental to the working of the generators producing electricity or electromagnetic radiation and to the presence of parasitic phenomena that disturb the operation of neighboring electrical machines. To circumvent this drawback, the accepted method is to see to it that the electrical machines are activated preferably when the electrical current of the mains passes through zero.
In the context referred to here above, in addition to the random character of the control information or instruction from the pilot wire, there is now the need to take account of the instant at which the mains supply passes through zero. This will ultimately contribute to further complicating the control circuit of the machine, namely the circuit for controlling the radiator in the case being described herein. Furthermore, just as the instruction from the pilot wires may be considered to take priority over the regulation control information or instruction, so is it now no longer possible to consider the control information or instruction related to the passage through zero of the electrical supply current as taking priority over the instruction from the pilot wires. Indeed, the fact of taking one instruction into account may, if priority is given to it, prevent the other instruction, which would be delivered simultaneously, from being taken into account.
Hence, the problem to be resolved is not only that of adding another microcontroller which would be used to manage another problem but also that of managing, at the same time, the problems of temporal conflict that may arise owing to the simultaneous nature of the two instructions. In general, this will also be the case when it is desired to provide a known type of operation of any machine with a first additional instruction and a second additional instruction.